http://dl.acm.org/citation.cfm?id=2207
A replicated database is a distributed database in which some data items are stored redundantly at multiple sites.
There are two correctness criteria for replicated databases: replication control — the multiple copies of a data item must behave like a single copy, insofar as users can tell; and concurrency control — the effect of a concurrent execution must be equivalent to a serial one.
Users interact with the DBS by running programs, called transactions, that issue reads and writes.